A growing interest has developed for the direct optical control of semiconductor devices due to the potential applications in phased array radar and communications. The following list of documents comprises a sample of articles (1-6) which concern the optical control of such devices, and a sample of articles (7-14) which concern the design and fabrication of resonant tunnel diodes.
1. A. S. Daryoush, "Optical Synchronization of Millimeter-Wave Oscillators for Distributed Architectures," IEEE Trans. Microwave Theory Tech., Vol. 38, pp. 467-476, May 1990; and a related article by, K. Kurokawa, "Injection Locking of Microwave Solid-State Oscillators," Proc, IEEE 61, 1386 (1973). PA0 2. A. J. Seeds and A. A. A. DeSalle, "Optical Control of Microwave Semiconductor Devices," IEEE Trans. Microwave Theory Tech., Vol. 38, pp. 577-584, May 1990. PA0 3. T. C. L. G. Sollner, E. R. Brown and H. Q. Le, "Microwave and Millimeter-Wave Resonant-Tunneling Devices," Lincoln Lab. Jour., Vol. 1, pp. 89-105, 1988. PA0 4. S. C. Kan, S. Sanders, G. Griffel, G. H. Lang, S. Wu, and A. Yariv, "Optical Switching of a New Middle Trace in an Optically Controlled Parallel Resonant Tunneling Device-Observation and Modeling," Appl. Phys. Lett., Vol. 58, pp. 1548-1550, 1991. PA0 5. P. England, J. Yee, L. T. Florez, J. P. Harbison and J. E. Golub, "Optical Switching in Resonant Tunneling Structures," Conference on Quantum Electronics Laser Science, May 12-17, 1991, Baltimore, Md., 1991 Technical Digest Series, Vol. 11, p. 34, 1991. PA0 6. D. J. Struzbecher, J. F. Harvey, T. P. Higgins, A. C. Paolella, and R. A. Lux, "Direct Optical Frequency Modulation of a Resonant Tunnel Diode Oscillator," submitted to IEEE Electron Device Lett., 29 Jul. 1991. PA0 7. L. L. Chang, L. Esaki and R. Tsu, "Resonant Tunneling in Semiconductor Double Barriers," Appl. Phys. Lett., vol. 24, pp. 593-595, 1974. PA0 8. I. Mehdi, R. K. Mains, and G. I. Haddad, "Effect of Spacer Layer Thickness on the Static Characteristics of Resonant Tunneling Diodes," Appl. Phys. Lett. 57, 899 (1990); and a related article by J. E. Oh, I. Mehdi, J. Pamulapati, P. K. Bhattacharya, and G. I. Haddad, "The Effect of Molecular Beam Epitaxial Growth Conditions on the Electrical Characteristics of In.sub.0.52 Al.sub.0.48 As/In.sub.0.53 Ga.sub.0.47 As Resonant Tunneling Diodes," J. Appl. Phys. 65, 842 (1989); I. Mehdi, R. K. Mains, G. I. Haddad, and U. K. Reddy, "Properties and Device Applications of Deep Quantum Well Resonant Tunneling Structures," Surf. Sci. 228, 426 (1990); and also by the same authors, R. K. Mains, I. Mehdi, and G. I. Haddad, "Effect of Spatially Variable Effective Mass on Static and Dynamic Properties of Resonant Tunneling Devices," Appl. Phys. Lett. 55, 2631 (1989). PA0 9. C. J. Arsenault and M. Meunier, "Proposed New Resonant Tunneling Structures with Impurity Planes of Deep Levels in Barriers," J. Appl. Phys. 66, 4305 (1989). PA0 10. R. L. Wang, Y. K. Su, Y. H. Wang, and K. F. Yarn, "Negative Differential Resistance of a Delta-Doping-Induced Double Barrier Quantum-Well Diode at Room Temperature," IEEE Electron Dev. Lett. 11, 428 (1990). PA0 11. K. Reddy, A. J. Tsao, S. Javalagi, G. K. Kumar, D. R. Miller, and D. P. Neikirk, "Quantum well injection transit time (QWITT) diode oscillators," in Conference Digest Fifteenth International Conference on Infrared and Millimeter Waves, 10-14 Dec 1990, Orlando, Fla., ed. R. J. Temkin, (SPIE vol. 1514), p. 88. PA0 12. J. M. Gering, T. J. Rudnick, and P. D. Coleman, "Microwave Detection Using the Resonant Tunneling Diode," IEEE Trans. Microwave Thry. and Tech. 36, 1145 (1988). PA0 13. T. C. L. G. Sollner, P. E. Tannenwald, D. D. Peck, and W. D. Goodhue, "Quantum Well Oscillators," Appl. Phys. Lett. 45, 1319 (1984); and a related article by, E. R. Brown, T. C. L. G. Sollner, W. D. Goodhue, and C. D. Parker, "Millimeter-Band Oscillations Based on Resonant Tunneling in a Double-Barrier Diode at Room Temperature," Appl. Phys. Lett. 50, 83 (1987). PA0 14. G. Keiser, Optical Fiber Communications, (McGraw-Hill, N.Y., 1983) and see C. K. Kao, Optical Fiber Systems: Technology, Design, and Applications, (McGraw, 1982).
As is evident from the above cited references, the technology of building resonant tunnel diodes (RTDs) is well established. As well, the technology of microwave light generation and delivery using lasers, light emitting diodes, plasma tubes and the like in combination with intensity modulators and fiber optics is also well known. Therefore, as is suggested by the above identified references, one skilled in the art would readily be able to design any number of optical or integrated optic systems to deliver light intensity modulated at microwave or millimeter wave frequencies in the nominally 2 mW power range with photon energies above the bandgap of a semiconductive device material to the semiconductive device and incorporate such a semiconductive device in oscillator circuit applications.
An example of important technical fields where such semiconductor devices would be able to be directly incorporated is in phased array radar and communication systems and in remote antenna systems. As suggested by references 1 and 2, intensity modulated light would modulate active oscillator modules using these semiconductor devices and distributed over an antenna array remote from the rest of the radar or communication system. One means of achieving modulation, as suggested by reference 2, is by modulating oscillators with a direct optical signal delivered over optical fibers. Reference 2 describes the various means which are available to optically control semiconductor devices, including the direct optical modulation of oscillators utilizing IMPATTS, FETs, and HEMTs. However, these semiconductor devices lack some of the enhanced performance characteristics of RTDs and, therefore, modulation or locking of oscillator modules would be further optimized by optically controlling RTDs incorporated in such oscillators.
The present invention addresses this present need for direct optical control of an RTD to modulate or lock an RTD oscillator.